This invention relates to an apparatus for welding non-circular shapes and, more particularly, to such an apparatus which is uniquely suited for making welds about the periphery of a polygonal shape.
Numerous equipments have hitherto been provided for controlling the rotation of a workpiece while simultaneously controlling the position of a welding torch in relation to the work for the purpose of providing uniform welds free of defects. For example, U.S. Pat. No. 2,280,627 granted Apr. 21, 1942 to V. J. Chapman relates to an automatic welding apparatus in which a workpiece is mounted on a turntable juxtaposed to the end of a welding torch or electrode with the line of the contour to be welded aligned in registration with a cam surface having a configuration corresponding to the the weld line and which controls the turntable to bring the weld line past the welding torch. The angle of the welding electrode relative to the work is adjustable, and it is automatically maintained at a predetermined distance from the workpiece by arc voltage responsive means. U.S. Pat. No. 3,126,472 granted Mar. 24, 1964 to J. H. Brems also relates to a contour welding machine. In the Brems apparatus, the speed of rotation of a workpiece is controlled by a cam, the contour of which maintains the linear rate of welding along the weld line constant despite changes in the radius of curvature of the workpiece along the weld line. Additional cams are provided to move the welding head and the welding torch carried thereby both horizontally and vertically in relation to the workpiece. Though representing different degrees of complexity, both of those machines leave much to be desired when extremely exacting welding standards are to be met. Although both machines provide an arrangement for maintaining the electrode-to-workpiece distance constant, neither provides any arrangement for maintaining the instantaneous attitude of the electrode to the workpiece constant during welding with a consequent impairment of the weld resulting from variations in weld penetration.